1. Field of the Invention:
This invention relates to an emergency locking retractor which can be released from lockup. By the term "lockup" as used herein is meant a phenomenon or situation in which subsequent to full take-up of a webbing, a take-up spindle for the webbing can still rotate slightly in a webbing-releasing direction but the locking of the take-up spindle cannot be released by the slight rotation of the take-up spindle in the webbing-releasing direction.
2. Description of Related Art:
Emergency locking retractors known to date have an inertia member. When the inertia member is delayed in rotation relative to its associated take-up spindle, the take-up spindle and a force-transmitting member are connected to each other by means of a clutch means and the force-transmitting member hence rotates together with the take-up spindle in a webbing-releasing direction. A cam portion of the force-transmitting member then acts on a driven portion of a pawl member to bring the pawl member into engagement with a ratchet means provided integrally with the take-up spindle, so that any further rotation of the take-up spindle in the webbing releasing direction is locked.
In such retractors, the force-transmitting member is rotated together with the take-up spindle, namely, with the ratchet means in the webbing-releasing direction by means of the clutch means. The pawl member is hence brought into a locking state in which the pawl member is brought into engagement with any one of teeth of the ratchet means by the cam mechanism. The pawl member can hence be brought into a locking state in synchronization with the rotation of the ratchet means. It is therefore possible to avoid the so-called jumping phenomenon that the edge of the pawl member is hit back by the teeth of the ratchet means and the intended engagement between the pawl member and any one of the teeth of the ratchet means cannot be achieved smoothly.
However, the clutch means is connected making use of an inertia force of an inertia member when a rotational offset occurs between the inertia member and the take-up spindle. As a result, the force-transmitting member rotates together with the take-up spindle to bring the pawl member into engagement with the ratchet means. Upon occurrence of the situation in which an inertia force is applied, the rotation of the take-up spindle in the webbing-releasing direction is locked through such a course of operation as described above even when no emergency situation exists and the locking of the take-up spindle is hence unnecessary.
When the webbing is taken up rapidly over the entire length thereof from a released state by the spring force of a take-up spring, the take-up spindle is abruptly stopped upon completion of tightening of the thus-wound webbing but the inertia member is allowed to rotate continuously owing to its inertia force. The inertia member thus undergoes a rotational offset relative to the take-up spindle, whereby the clutch means is brought into a connected state. The take-up spindle then begins to rotate in the webbing-releasing direction as a reaction. Accordingly, the force-transmitting member starts rotating in the webbing-releasing direction together with the take-up spindle via the clutch means which is in such a connected state as described above.
Rotation of the force-transmitting member hence brings the pawl member into a state where it is engageable with the ratchet means. As a result, the take-up spindle becomes no longer rotatable in the webbing-releasing direction once the ratchet means engages the pawl member. Since the webbing is in a fully-wound state here, the take-up spindle cannot rotate in the webbing-winding direction either. The webbing can thereafter be released and taken up only within a narrow range between a state, in which the pawl member is engageable with the ratchet means as described above, and another state in which the pawl member is actually brought into engagement with the ratchet means. Neither release nor winding of the webbing hence becomes feasible as a matter of fact, so that the retractor goes into the so-called lockup state.